Process for making floating soap



Oct. 10, 19 50 A. L. SCHULERUD 2,525,081

' PROCESS FOR MAKING FLOATING SOAP Filed Aug. 6, 1949 awe/rm" Albart Lyle Sch u/cr'uc Patented Oct. 10, 195

PROCESS FOR MAKING FLOATING SOAP Albert Lyle Schulerud, Nutley, N. J., assignor to Colgate-Palmolive-Peet Company, Jersey City, N. J a corporation of Delaware Application August 6, 1949, Serial No. 109,044

7 Claims.

This invention relates to a process for making soap which has a specific gravity less than water, and is especially concerned with a process for economically making floating soap of toilet soap quality.

Floating soaps of framed soap quality have long been made and used. Conventional methods of making these floating framed soaps are, however, time-consuming and require considerable labor. The soap is permitted to solidify and age in bulk for several days after air has been incorporated into it, and the labor in handling the soap and the fragments produced in cutting it into bars is considerable. Also, much valuable plant space is taken up for storage of the solidiiying soap. An additional disadvantage is that framed floating soap is less soluble than milled soap and bars made therefrom are subject to objectionable warping and distortion.

Recently other methods of providing a floating soap have been advanced which depend upon incorporation of air in the soap mass at an elevated temperature where the soap is molten or semi-molten, followed by agitation to obtain a fine distribution of air. In one case it was proposed to work the soap during cooling to a temperature sufficientlylow that a, phase change occurred from the less soluble phase of framed type soap to the more soluble phase of milled soap. These processes require special equipment and in some cases special formulation to produce commercally acceptable product. The present invention overcomes these disadvantages of the prior art.

It has now been discovered that floating soap of high quality and desirable properties heretofore possessed only by milled soap can be produced by agitating or working a mass of soap fragments having a predetermined moisture content and interstitial air under controlled temperature conditions which inhibit remelting of the soap mass while heating it sufficiently to make it soft enough to retain air entrained in the fragments, which is broken up and finely dispersed throughout the mass during the working, and extruding the aerated mass as a form-retaining column or bar. Except for the intentional introduction and retention of air and special control of moisture content, temperature, and possibly other conditions,

the preferred process of the invention may in- 'volve substantially the same procedure as that used for making milled toilet soap, although certain phases may be altered as will appear.

With the above in mind, it is a major object of my invention to provide a novel method of making floating soap of toilet soap quality which is free of complexity, efficient, and extremely economical, even more economical than present commercial methods of making floating framed soaps, and which may be carried out with little or no modification of standard apparatus for making toilet soap.

A further object of the invention is to provide a novel process of making a floating soap of toilet soap quality wherein cooled and dried soap is worked and aerated under controlled predete mined temperature and moisture content conditions.

A further object of the invention is to provide a novel process for making floating soap of toilet soap quality wherein cooled kettle soap is dried to a moisture content between and 30% and is then worked in a plodder or like device under controlled temperature conditions which maintain the soap mass plastic and capable of incorporation of air therein but which do not liquefy the soap. Preferably the temperature of the soap is maintained below 130 F.

A further object of the invention is to provide a, novel process for making floating soap wherein milled soap is aerated under controlled moisture content and temperature conditions.

Further objects of the invention will appear as description proceeds in connection with the ap-- pended claims.

The process of the present invention comprises introducing a mass of solid soap fragments having a moisture content of about 15% to 30% and interstitial air into a zone where the mass is worked to disperse the air uniformly and finely throughout the mass. The temperature of the soap is maintained sufficiently high to render it plastic enough to retain entrained and subdivided air in sufiicient amount to float readily. The aerated mas-s is then extruded in a continuous bar or column for further processing.

The usual ingredients for making toilet soap may be saponified in any desired manner, e. g., in a kettle the soap is mixed while liquid in a crutcher with any desired additives, e. g., a suitable preserving agent, and then cooled to -90 F. to solidify the soap. These steps may be the same as if usual toilet soap were being manufactured. Of "course, some air is incorporated in the soap during, the operation of the paddle in the crutcher, but it is immaterial to the invention whether or not any air becomes incorporated in the soap at this time.

At this point in the manufacture of ordinary toilet soap, it the accepted procedure to dry the cooled and solidified soap in a suitable dryer tunnel or like apparatus to a moisture content of about 7a to 14%. In the present invention the soap may be passed through such a drying apparatus, but the soap is dried to a moisture content of approximately to the exact moisture content depending on the other conditions of the process and the composition of the soap mass.

The partially dried soap may then, as in the usual process of making toilet soap, be conveyed to an amalgamator where perfume, whitening agents, necessary preservatives or coloring agents are added, and then conveyed to the usual milling rollers where the soap is formed upon the rollers as a thin continuous ribbon having a thickness, for example, of only about .025 inch. In practice I maintain the milling rollers at a surface temperature of about 100 to 115 R, which imparts about the same temperatures to the soap ribbon. The advantage of having the soap ribbon leave the milling rollers at a temperature of at least 100 to 115 F. in the invention is that the soap will enter the working zone, which it does in the next step in the process, in a warm condition almost at the level of the temperature at which it is to be worked, and less heat is required to be imparted to the mass to bring it to desired plasticity as it passes through the working zone.

Since the purpose of the milling operation in the manufacture of usual toilet soap is chiefly to work the soap mass thoroughly and disperse and distribute the ingredients added in the amalgamator, and since in the present invention the soap i thoroughly agitated and worked while the air is being incorporated, it may be desirable in practicing the invention in some instances to eliminate the milling step and introduce the solidified soap directly into the working zone. The desirable preheating of the solidified soap to about 100 to 115 F., accomplished in the preferred embodiment of the invention by the milling rolls, may be performed by any suitable equivalent apparatus.

A plodder which has been found to be satisfactory for agitating the soap mass and introducing air into it is illustrated in the drawing wherein an upper worm II is rotatably disposed within a cylinder l2. Warm milled soap is introduced into opening [3 and fed from left to right by rotation of worm ll.

Cylinder i2 is formed with heat transfer fins l4 and is surrounded by an annular water jacket 15 provided with suitable water inlet and outlet conduit connections (not shown) for maintaining the temperature of the wall of cylinder [2 under close control.

Across its discharge end, cylinder l 2 has rigidly secured thereto a perforated plate [6 formed with a series of tapered apertures I! through which soap is forced by the action of worm II. A grinding head l8 rigid with rotatable worm l 1 comprises a large number of radially arranged knife blades which scrape across the inner surface of plate 16. Another scraper, comprising a four-bladed knife H3, is secured to worm ll externally of plate I6 and wipes across the opposite surface of plate l6.

Beyond cylinder [2, the soap enters into a chamber 2i which is open at its bottom to discharge into a bottom cylinder 22 having a rotatable bottom worm 23 adapted to feed the soap from right to left through the cylinder. Cylinder 22 is also formed with heat exchange fins 24 and is surrounded by an annular water jacket 25 like upper jacket 15, for accurate control of the wall temperature of cylinder 22.

At the left end of cylinder 22 is a decreasingly tapered discharge nozzle 28, called a plodding nozzle, through which the soap is extruded as a continuous bar of desired cross-section. A suitable water jacket 27 surrounds the nozzle 26 near its discharge end for providing a surface conditioning treatment of the extruded soap.

Further details of a plodder of this type are disclosed in Schwantes Patent No. 2,146,770, to which reference is hereby made for further detail.

During operation according to the preferred embodiment of the invention, the warm milled soap, which may be in ribbon, chip, pellet or other suitable fragment form, is introduced through opening [3 and is compressed and worked and fed toward chamber 2: by rotation of worm H. Air is carried into the plodder in the spaces between the soap fragments. The soap mass undergoes its greatest agitation as the grinding head I 8 rapidly cuts across the flowing soap mass at plate l6. During its traverse through cylinder I2, I raise the temperature of the soap mass until the mass i sufiiciently plastic to retain the air, but that temperature is prevented from going above 130 F. to prevent reliquefaction and attendant change in phase of the soap. Preferably the soap mass has a temperature of about F. to F. as it passes through the point of maximum agitation, and this temperature range has been found to be optimum for aeration of the soap.

The agitator action of plate [6 and the blades of head [8 and knife [9 apparently repeatedly subdivides the relatively large air bodies which are entrained in the soap during traverse of cylinder [2, and the smaller air bodies, which under the microscope appear to be irregularly shaped and arranged, are distributed and discrete within the soap mass. At this point of maximum agitation the soap is also of such plasticity as to have optimum air retentivity. It will be understood that any substitute agitator device may be used for the same purpose.

The soap mass as it enters chamber 2| is a relatively spongy mass, and it is passed through the second or lower worm in order to compress it and extrude it in desired shape and condition. During its passage through the lower cylinder 22, the soap mass is maintained at substantially the temperature at which it was aerated, and as it extrudes through nozzle 26, its surface is given a surface conditioning treatment for insuring a smooth, attractive finish on the bar.

The action of Worms H and 23 is to compress and work the soap, and they do not appreciably affect the amount of air distributed in the soap since the plasticity of the soap prevents the air from being squeezed out by worm pressure.

It will be noted that the process of the invention here departs from the usual process of makmg milled toilet soap wherein chamber 2! was evacuated to remove the air from the soap in that chamber 2| contains air at atmospheric pressure in the process of the invention.

In passing the high moisture content milled soap through the plodder and working it to incorporate therein en'ough air to make it fioat, I maintain the jacketed walls of the chambers of the plodder at sufficiently high teinpsratiue to make the soap mass adequately plastic arid soft for incorporating and retaining the air therein and for enabling the mass to be thoroughly Worked and kneaded during the relatively short period of its passage through the plodder, and at the same time I maintain those temperatures uniformly low enough that the soap mass is not raised above its critical temperature which separates its given milled soap phase from another phase in which its colloidal characteristics may be entirely different. The moisture content and the temperature of the soap mass may be varied in interdependent relation. At the higher moisture contents, lowe aerating temperatures are possible. I am able to maintain the soap mass adequately plastic for incorporation of air at lower temperatures than hitherto considered possible with any given moisture content. It is this careful control of the temperature of the soap mass during its passage through the plodder that is a very important feature of the present invention.

In practicing the invention I have found it desirable to mainatin the chamber wall temperatures of the plodder in the neighborhood of about between 125 to 170 F., and preferably in the range between 130 and 140 F. The top barrel may be provided with water at a different temperature from the lower barrel, e. g., 90 to 180 F. and preferably 130 to 140 F. for the upper and 90 to 100 F. for the latter.

It is usually necessary to maintain the cylinder wall temperatures higher than the desired aerating temperature of the soap mass (105 F. to 125 F.) because the incoming soap must be quickly heated to that desired temperature during its short period of traverse of each plodder cylinder. The heat insulating properties of the soap itself, coupled with the mixing action and movement of the soap mass through the plodder, are

such that only the small amount of soap in direct I contact with the cylinder walls may be heated higher than 130 F., and the temperature of the main body of the soap mass does not rise above 115 to 125 F.

The water jackets provide a very accurate control over the soap temperature. stances I have found that jacket 21 may be held at alower temperature than jacket l5, because the soap mass requires more heat to bring it up to aerating temperature in the upper worm than is required to maintain that temperature in the lower worm.

I have found it desirable that the nozzle temperature of the plodder should be about 110'F. to 150 F., the temperature regulating water jacket 21 being here provided for controlling the temperature in the region of the plodde nozzle. The purpose of this control is to produce a smooth, uniform surface on the extruded soap bar.

During its passage through the plodder, the high moisture content warm plastic soap mass undergoes substantially the same mechanical treatment that the usual toilet soap undergoes during passage through the same type of plodder. The major differences are that the temperatures of the present process are maintained much higher than in the conventional toilet soap making process and no attempt is made to evacuate air from the soap. I have found that there is no In some in-' need for trying to force air into the soap, as the 7 tion as other apparatus maybe used which will agitate the soap fragments and air to provide a fine dispersion and extrude it as a bar or column. For example, a jacketed cylinder with a pump feed for the soap fragments at one end, a nozzle at the other end, and a power driven agitator such as a shaft having radial arms to subject the soap to shear and preferably to scrape it also from the cylinder wall is satisfactory.

The prevailing temperature of the soap mass in the plodder and the moisture content of the soap may be relatively adjusted and carefully controlled to obtain a desired regulation of the quality and specific gravity of the product. The composition of the soap itself is also a factor which must be considered in predetermining the moisture content and soap temperature in the process. For example, where the ingredients are mainly coconut oil and tallow, as the amount of coconut oil in proportion to the tallow is increased, I find it desirable to increase both the moisture content of the milled soap and the temperature of the soap mass in the plodder, as will be apparent from the examples given below.

Example I The following formulas are used:

Kettle Soap-15% Coconut Oil Tallow Crutcher formula:

185 lbs Kettle Soap 98. 358% 3 lbs. 2 025.... N Silicate (preservative) 1.642%

188 lbs. 2 025. 100. 000%.

This crutcher formula was passed over a chilling roll and the resultant chips dried to 21% The saponified kettle soap was run into a 200- 1b. paddle crutcher and the N-silicate added while crutching at slow speed. The speed was then increased to the limit of the machine and crutching continued for ten minutes. During this period some aeration occurred but was not essential. This mixture was then run to a standard chip dryer and dried to about 21% moisture using 0.017 chip thickness and -100 F. dryer tunnel temperature. These chips were then weighed into -a toilet soap amalgamator in the formula amount and the required titanium dioxide and perfume added. Mixing was continued for a minimum of four minutes after all of the ingredients were in. The mixture was then milled twice on a 3-roll mill preheated to a temperature from to F.

It was necessary to set the particular milling equipment to give a fairly heavy chip (0.025 inch thick) in order to get satisfactory transfer of the soap from one roll to the other, The warm milled ribbons thus produced were fed to the plodder as quickly as possible after milling. The

plodder circulating water in the barrels was heated to an average temperature of F. and the nozzle temperature set at 110 F.

Theplodder bar produced with this set-up is cut into cake-size pieces, stacked in traysfor 16 hours or more, and then pressed and wrapped.

Example II The second process was similar to the one already described, except that the kettle soap formula contained 25% coconut oil and 75% tallow. This kettle soap was used in the same manner as the previous one in all formulation, but dried to about 25% moisture. In the plodding operation, the plodder barrel temperature was 140 F. instead of 130 F., and the nozzle temperature was 120 F. instead of 110 F The temperature of the extruded soap in the process in one instance was 122 F.

One pass through the plodder in either of the above examples gives a soap which ha a specific gravity of 0.91 to 0.92 as the soap is extruded. After pressing, this specific gravity ranges from 0.94 to 0.96. If the soap is circulated through the plodder assembly for a second pass, the specific gravity will be reduced to approximately 0.85 before pressing.

The structure of the air dispersed in soap made in this manner appears through a IO-power microscope as non-uniformly distributed clusters of short cracks. These clusters are not uniform in size and with the processes described above they will have an average diameter of about 0.010 of an inch.

I have found that the air retentivity of the soap may be advantageously increased in the process by adding to the soap mass, usually in the crutcher while the soap is liquid, a suitable plasticizer such as glycerol monostcarate or monoglycerides of mixed acids of coconut oil. The action of the plasticizer is apparentl to increase the toughness of the soap mass and strengthen the wall of the pocket enclosing the subdivided air bodies.

Example III A third process was similar to Example II, ex-

cept that 1% of the monoglyceride of coconut oil acids was incorporated in the crutcher formula. Also a 12-inch Schwantes plodder was used to complete the processing of the soap formulated according to the mixer formula. This plodder was modified by mounting a cone-shaped homogenizing unit on the top barrel in the space nornally occupied by the vacuum chamber and by separating the water jackets to the top and bottom barrels so that each barrel could be maintained at a diiierent and independent temperature level.

In the plodding operation th top barrel water jacket temperature was 170 F. which was sufficient to cause the temperature of the soap mass coming out of the homogenizing unit to be 113 F, The bottom barrel water jacket temperature was 105 F. and the plodder nozzle temperature was 125 F.

One pass through the plodder under the described conditions and at a rate of 1,080 pounds per hour gave a soap with a specific gravity of 0.90 to 0.92 as the soap was extruded.

The moisture content of the soap treated by this process may be reduced if potassium soap is substituted for a portion of the sodium soap. The potassium soap is preferably maintained below about 20% of the total soap content. For each 5% of potassium soap the moisture content of the total soap mass may be reduced about 2%. This mixed soap appears to produce a finer texture than when sodium soap alone is used,

If desired also, a pressure plate having about inch circular apertures may be provided in nozzle 21 for providing smoother extrusion of the soap bar.

Soap produced according to my above-described 8 process is of toilet soap quality and floats in water. The process is economical and may be carried out in standard apparatus used in the commercial manufacture of soilet soap, or by relatively inexpensive special apparatus. It will be appreciated that considerable departure may be made from the illustrated plodder structure while achieving the advantageous process steps of the invention.

I believe that this is the first time that air has been successfully incorporated in non-liquid soap so as to produce a floating soap of toilet soap quality.

Although the present invention has been described with respect to particular embodiments and examples thereof, it wil1 be understood by those skilled in the art that other variations and modifications of the invention can be made and that various equivalents can be substituted therefor without departing from the principles disclosed herein.

The present application is a continuation-inpart of applicants copending application No. 591,937 filed May l, 1945, now abandoned.

What is claimed is:

1. The process of making floating soap having the phase structure of milled soap which comprises the steps of introducing a mass of solid soap fragments having a moistiu'e content of about 15% to 30% into a chamber wherein the soap mass is worked in shear and compression, air carried into the chamber in the spaces between the fragments being entrained and subdivided within the worked mass during said working, maintaining the temperature of the soap mass during said working sufiiciently high to render it plastic enough to retain entrained and subdivided air in sufiicient amount to reduce the specific gravity of the soap so that it will readily float in water but below F., and extruding the aerated soap mass in a continuous shape retaining column suitable for further handling 2. In a process of making floating soap wherein a mass of milled soap fragments having a moisture content of 15% to 30% is worked within a plodder of the type usually employed in the manufacture of toilet soap, air being carried into the plodder in the spaces between the fragments of the mass, the steps of plodding the soap mass in heat softened condition in which it is sui'hciently plastic to retain enough entrained and subdivided air to produce an aerated mass of such specific gravity that it will float in water while maintaining the temperature of said soap mass below 130 F., and extruding the aerated soap mass as a continuous shape retaining column.

3. The process of making floating soap having the phase structure of milled soap which comprises the steps of cooling molten soap to solid condition, drying the cooled solid soap to approximately 15% to 30% moisture content, milling the dried soap, charging a plodder with a mass of said milled soap fragments, plodding said mass, air carried into the plodder in the spaces between said fragments being entrained and subdivided within the soap mass during plodding, maintaining the temperature of the soap below 130 F. during milling and plodding and sufiiciently high during plodding that the mass is plastic enough to retain sufiicient air to make the soap float, and extruding the aerated soap mass as a continuous shape retaining column.

4. The process of making floating soap which comprises forming soap fragments having a moisture content of 15 to 30 introducing said fragments and entrained air into a working zone, working said fragments at a temperature under 130 F. to subdivide and disperse said air throughout the mass while the soap is sufiiciently plastic to retain enough subdivided and dispersed air to impart floating properties thereto, and extruding the aerated soap as a bar.

5. The process of making floating soap which comprises forming soap fragments having a moisture content of 15% to 30%, continuously introducing said fragments and entrained air into a working zone, working said fragments at a temperature under 130 F. to subdivideand disperse said air throughout the mass while the soap is sufliciently plastic to retain enough subdivided and dispersed air to impart floating properties thereto, and continuously extruding the aerated soap as a bar.

6. The process of making floating soap as set forth in claim in which the working is effected by the shearing and compressive forces generated by a screw.

7. The process of making floating soap which comprises forming soap fragments having a moisture content of 15% to 30%, continuously introducing said fragments and entrained air into a plodder, plodding said fragments at a temperature under 130 F. to subdivide and disperse said air throughout the mass while the soap is sufiiciently plastic to retain enough subdivided and.

dispersed air to impart floating properties thereto, and continuously extruding soap as a bar.

ALBERT LYLE SCHULERUD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,532,693 Gottschalk Apr. 7, 1925 2,005,333 Bodman June 18, 1935 2,146,770. Schwantes Feb. 14, 1939 2,215,539 Bodman Sept. 24, 1940 2,226,075 Rowe Dec. 24, 1949 2,295,594 Mills Sept. 15, 1942 2,377,424 Ittner June 5, 1945 2,398,776 ,Bodman Apr. 23, 1946 FOREIGN PATENTS Number Country Date 553,519 Great Britain May 25, 1943 OTHER REFERENCES Gathman, American Soaps, 2d edition, 1899, page 357. 7

Industrial and Engineering Chemistry, vol. 35, No. 9, Sept. 1943, pages 1005-1012. 

1. THE PROCESS OF MAKING FLOATING SOAP HAVING THE PHASE STRUCTURE OF MILLED SOAP WHICH COMPRISES THE STEPS OF INTRODUCING A MASS OF SOLID SOAP FRAGMENTS HAVING A MOISTURE CONTENT OF ABOUT 15% TO 30% INTO A CHAMBER WHEREIN THE SOAP MASS IS WORKED IN SHEAR AND COMPRESSION, AIR CARRIED INTO THE CHAMBER IN THE SPACES BETWEEN THE FRAGMENTS BEING ENTRAINED AND SUBDIVIDED WITHIN THE WORKED MASS DURING SAID WORKING, MAINTAINING THE TEMPERATURE OF THE SOAP MASS DURING SAID WORKING SUFFICIENTLY HIGH TO RENDER IT PLASTIC ENOUGH TO RETAIN ENTRAINED AND SUBDIVIDED AIR IN SUFFICIENT AMOUNT TO REDUCE THE SPECIFIC GRAVITY OF THE SOAP SO THAT IT WILL READILY FLOAT IN WATER BUT BELOW 130*F., AND EXTRUDING THE AERATED SOAP MASS IN A CONTINUOUS SHAPE RETAINING COLUMN SUITABLE FOR FURTHER HANDLING. 